US4597293A - Scanning acoustic microscope - Google Patents

Scanning acoustic microscope Download PDF

Info

Publication number
US4597293A
US4597293A US06/689,955 US68995585A US4597293A US 4597293 A US4597293 A US 4597293A US 68995585 A US68995585 A US 68995585A US 4597293 A US4597293 A US 4597293A
Authority
US
United States
Prior art keywords
sample
acoustic
cover member
acoustic impedance
propagating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US06/689,955
Other languages
English (en)
Inventor
Hiroshi Kanda
Isao Ishikawa
Kageyoshi Katakura
Chitose Nakaya
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Assigned to HITACHI, LTD., A CORP OF JAPAN reassignment HITACHI, LTD., A CORP OF JAPAN ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: ISHIKAWA, ISAO, KANDA, HIROSHI, KATAKURA, KAGEYOSHI, NAKAYA, CHITOSE
Application granted granted Critical
Publication of US4597293A publication Critical patent/US4597293A/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/06—Visualisation of the interior, e.g. acoustic microscopy
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02854—Length, thickness

Definitions

  • the present invention relates to an acoustic imaging apparatus which exploits high-frequency acoustic energy. More particularly, it relates to an acoustic microscope of the reflection type in which a focused ultrasonic beam is projected on a sample so as to obtain an image on the basis of the resulting reflected acoustic waves.
  • a scanning acoustic microscope has been proposed and studied as an apparatus for obtaining an image expressive of the microscopic elastic properties of an object to-be-observed by utilizing a hypersonic wave which has an acoustic frequency of 1 GHz and accordingly exhibits an acoustic wavelength of approximately 1.5 ⁇ m in the water.
  • an acoustic lens whose F number is small is employed for projecting an ultrasonic beam which is very sharply focused on a sample to-be-observed through a propagating medium such as water.
  • a propagating medium such as water.
  • perturbed energy from the sample is detected, and the detected acoustic waves are displayed on a CRT screen.
  • microscopic images are obtained.
  • Setups for detecting the perturbed energy from the sample as described above are classified into two types; the transmission type and the reflection type.
  • the transmission type acoustic waves having passed through the sample are detected to obtain an image. Therefore, a transmitting acoustic lens or a transmitting concave transducer and a receiving acoustic lens or a receiving concave transducer are arranged so as to oppose to each other with the sample interposed therebetween. Since the two, transmitting and receiving lenses or concave transducers must be arranged in confocal fashion, adjustments for the alignment thereof become complicated and very subtle.
  • a biological tissue which is an important object to be imaged by the acoustic microscope has heretofore been observed with the transmission type apparatus, not with the reflection type apparatus.
  • water or a physiological salt solution is used as a propagating medium and is held between the opposing transducers.
  • the sample is supported within this medium in the state in which it is stuck to a film of a thickness and a material that permit the presence thereof to be neglected in propagating the acoustic waves from the medium to the sample.
  • An object of the present invention is to provide an acoustic microscope in which even a sample slightly differing in the acoustic impedance from a propagating medium can produce intense reflected acoustic waves, whereby a good image is offered by a reflection type setup.
  • the characterizing feature of the present invention consists in a construction in which, between a sample and a propagating medium, a cover member greater in the acoustic impedance than the two is interposed.
  • the acoustic microscope of the present invention comprises a transducer unit which transmits an ultrasonic beam converging into a predetermined focus and which detects reflected acoustic waves caused by the transmission, holding means to hold a sample at and near the focus, scanning means to scan relative positions of the sample held by the holding means and the transducer unit, and a propagating liquid medium which fills a gap between the holding medium and the transducer unit, the holding means including a cover member which is interposed between the sample and the propagating medium and which has an acoustic impedance greater than those of the two.
  • Such construction effectively utilizes multipath reflection within the cover member for image display. Since the intensity of a reflection signal produced through the cover member depends upon the acoustic impedance of the sample located behind the cover member, the distributions of the elastic properties of the sample such as the acoustic impedance can be observed clearly.
  • FIG. 1 is a sectional view showing the principle of the present invention
  • FIG. 2 is a graph showing the characteristics of reflection factors versus the acoustic impedances of samples
  • FIG. 3 is a block diagram showing an embodiment of the present invention.
  • FIG. 4 is a sectional view showing an example of a transducer for use in the embodiment.
  • FIG. 5 and FIGS. 6A and 6B are sectional views showing aspects of performance of the present invention.
  • FIG. 1 is a view for explaining the principle of the present invention, which shows a transducer unit 40 having an acoustic lens, a sample 60, a propagating medium 70 (in case of a biological tissue, water or a physiological salt solution is usually used) filling the interspace between the lens and the sample, and an ultrasonic cover member 5 of thickness d forming the characterizing feature of the present invention.
  • An ultrasonic beam 7 radiated from the lens of the transducer unit 40 is reflected by the upper surface (surface l 1 ) and lower surface (surface l 2 ) of the cover member 5.
  • the situation of multipath reflection within the cover member differs depending upon the thickness of the cover member and the acoustic impedance (Z L ) and propagating velocity (v L ) thereof.
  • Z L acoustic impedance
  • v L propagating velocity
  • r denotes the ratio of the acoustic pressure of reflected ultrasonic waves coming out to the side of the propagating medium 70 as indicated by a plurality of arrows 51 in FIG. 1, relative to the acoustic pressure of the incident acoustic wave, namely, the reflection factor of the system illustrated in FIG. 1.
  • This quantity r is evaluated by the following equation: ##EQU1##
  • f denotes an ultrasonic frequency used
  • Z L , Z W and Z S denote the acoustic impedances of the cover member 5, propagating medium 70 and sample 60 respectively
  • d denotes the thickness of the cover member 5.
  • the absolute value of the acoustic-pressure reflection factor is given by: ##EQU2##
  • the abscissa represents the acoustic impedance Z S of a sample while the ordinate represents the reflection factor, and the situation of the changes of the reflection factor is illustrated with a parameter being the acoustic impedance Z L of the quarter-wave plate.
  • the acoustic impedance Z W of the medium is 1.5 ⁇ 10 6 MKS. That is, a case of employing water as the propagating medium 70 is assumed.
  • the acoustic impedance Z S of a biological tissue is distributed near 1.5 ⁇ 10 6 MKS being the acoustic impedance of water because the content thereof consists mostly of water or a physiological salt solution. Accordingly, reflected ultrasonic waves are not detected in the area of the greater part of the sample.
  • the circumstances are the most important reason why the transmission method has heretofore been employed for the observation of the biological tissue without using the reflection method.
  • the present invention is intended to eliminate the very difficulty.
  • Curves (b), (c) and (d) in FIG. 2 are the characteristics of the reflection factor in the cases where the acoustic impedances Z L of the cover members are 1.83 ⁇ 10 6 MKS, 4.0 ⁇ 10 6 MKS and 13.1 ⁇ 10 6 MKS, respectively. As seen from these curves, the acoustic pressure of the reflected acoustic waves is enhanced more with increase in Z L .
  • the acoustic impedance Z S of the sample When the acoustic impedance Z S of the sample is distributed above and below the acoustic impedance Z L of the cover member, the situation occurs in which the reflection intensity and the acoustic impedance of the sample do not correspond in 1-to-1 fashion as in the curve (a) and which is very inconvenient for the interpretation of an image. It is understood that, in order to prevent such situation, the acoustic impedance of the cover plate needs at least to be greater than the acoustic impedance of the sample. Further, in the case of the biological tissue, the acoustic impedance is distributed within a range of approximately 0.6-2.0 ⁇ 10 6 MKS.
  • the acoustic pressure of reflected acoustic waves is distributed within a range of at least -25 dB in comparison with that in the case of total reflection (refer to the curve (b)). Since the acoustic pressure of -25 dB can be deemed the lower limit permitting the detection of the reflected waves with the acoustic microscope, it is favorable for such biological tissues that Z L is 1.83 ⁇ 10 6 MKS or greater. In the case where Z L is 4 ⁇ 10 6 MKS as in the curve (c), the acoustic pressure of reflected waves is more enhanced, and a received signal of high signal-to-noise ratio can be obtained.
  • Z L 13.1 ⁇ 10 6 MKS as in the curve (d)
  • imaging is possible without a singular point in a range of greater acoustic impedances Z S of the sample, for example, from 0.6 to 10 ⁇ 10 6 MKS.
  • the range of the acoustic impedances of such samples can reach 10 ⁇ 10 6 MKS.
  • FIG. 3 shows the whole arrangement of an embodiment of the present invention.
  • a transducer unit 40 is composed of an acoustic lens 42 which is provided with a concave semispherical hole at one facet thereof, and a piezoelectric element 44 which is mounted on the other facet of the acoustic lens.
  • a signal source 10 and a receiver 12 are connected to the piezoelectric element 44.
  • an exciting signal in the form of pulses is applied from the signal source 10
  • an ultrasonic beam converging toward a predetermined focus is transmitted through a propagating medium 70.
  • a sample holder 80 for holding a sample 60 has a cover member 5 installed thereon, and the sample is stuck to the rear side of the cover member 5.
  • the ultrasonic beam enters the sample through the medium 70 as well as the cover member 5. Reflected waves thus produced are detected by the transducer unit 40 through the medium 70, and the detection signal is received by the receiver 12 and is applied to an image display portion 18 as imaging data. Meanwhile, the sample holder 80 is mechanically scanned and driven by a driving portion 16, and the image display portion 18 performs signal processing corresponding to the scanning and displays the image of the sample.
  • the driving portion may drive and scan the relative positions of the focus of the transducer unit and the sample, and may of course drive the transducer unit 40.
  • the transducer unit 40 may be an ultrasonic transducer having a predetermined focus. Therefore, it may well be the so-called concave transducer, for example, one in which a piezoelectric element 45 is mounted on the semispherical concave surface of a substrate 46 as shown in FIG. 4.
  • the sheet 52 was stuck to a metal ring 51 having a diameter of 20 mm and a thickness of 5 mm, and a sample 60 was stuck to the rear side thereof.
  • the resultant structure was set on the sample holder 80 of a reflection type acoustic microscope, and the sample was observed. The rear of the sample 60 is surrounded with the air.
  • the present invention even for a biological tissue whose acoustic characteristics are very close to those of water and which is difficult of imaging with the reflection type, there are attained the effects (1) that equivalently a very great reflection signal is obtained, and a reflected image of high signal-to-noise ratio can be obtained, and (2) that the singular point of a reflection signal which is determined by a medium used is removed, and the distribution of a reflection intensity and the distribution of an acoustic impedance within the surface of a sample correspond in 1-to-1 fashion, so a clear image display is possible.
  • the cover member functions as a protective film for the sample, there is the effect that the invention is convenient for samples, such as swelling samples, which are improper for direct contact with water or a salt solution as the medium.

Landscapes

  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Chemical & Material Sciences (AREA)
  • Multimedia (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)
US06/689,955 1984-01-11 1985-01-09 Scanning acoustic microscope Expired - Fee Related US4597293A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP59-1947 1984-01-11
JP59001947A JPS60146152A (ja) 1984-01-11 1984-01-11 超音波顕微鏡

Publications (1)

Publication Number Publication Date
US4597293A true US4597293A (en) 1986-07-01

Family

ID=11515804

Family Applications (1)

Application Number Title Priority Date Filing Date
US06/689,955 Expired - Fee Related US4597293A (en) 1984-01-11 1985-01-09 Scanning acoustic microscope

Country Status (5)

Country Link
US (1) US4597293A (de)
JP (1) JPS60146152A (de)
CA (1) CA1225733A (de)
DE (1) DE3500640C2 (de)
GB (1) GB2153997B (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5627320A (en) * 1988-03-23 1997-05-06 Texas Instruments Incorporated Apparatus and method for automated non-destructive inspection of integrated circuit packages
US5922961A (en) * 1996-05-10 1999-07-13 The United States Of America As Represented By The Secretary Of Commerce Time and polarization resolved acoustic microscope
EP1308750A3 (de) * 2001-10-18 2004-02-04 ContiTech Luftfedersysteme GmbH Verfahren und Anordnung zur Abstands- und Druckmessung innerhalb einer Luftfeder
US20070015993A1 (en) * 2005-07-13 2007-01-18 Clemson University Microwave imaging assisted ultrasonically
JP2015090281A (ja) * 2013-11-05 2015-05-11 パナソニックＩｐマネジメント株式会社 超音波測定方法および装置

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2602043B1 (fr) * 1986-07-24 1990-10-12 France Etat Procede de mesure non destructive du profil d'une surface
CN1019919C (zh) * 1990-03-08 1993-02-17 清华大学 具有新型声镜的反射式声显微镜
JP5124741B2 (ja) * 2006-03-13 2013-01-23 本多電子株式会社 音響インピーダンス測定方法、及び音響インピーダンス測定装置
JP5130451B2 (ja) * 2007-02-27 2013-01-30 国立大学法人豊橋技術科学大学 音響パラメータ測定装置、音響パラメータ測定装置用の試料支持体、音響パラメータ測定方法、及び超音波脳組織観察方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4205686A (en) * 1977-09-09 1980-06-03 Picker Corporation Ultrasonic transducer and examination method
US4503708A (en) * 1983-02-07 1985-03-12 Board Of Trustees Of The Leland Stanford Junior University Reflection acoustic microscope for precision differential phase imaging

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4205686A (en) * 1977-09-09 1980-06-03 Picker Corporation Ultrasonic transducer and examination method
US4503708A (en) * 1983-02-07 1985-03-12 Board Of Trustees Of The Leland Stanford Junior University Reflection acoustic microscope for precision differential phase imaging

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5627320A (en) * 1988-03-23 1997-05-06 Texas Instruments Incorporated Apparatus and method for automated non-destructive inspection of integrated circuit packages
US5641906A (en) * 1988-03-23 1997-06-24 Texas Instruments Incorporated Apparatus and method for automated non-destructive inspection of integrated circuit packages
US5922961A (en) * 1996-05-10 1999-07-13 The United States Of America As Represented By The Secretary Of Commerce Time and polarization resolved acoustic microscope
EP1308750A3 (de) * 2001-10-18 2004-02-04 ContiTech Luftfedersysteme GmbH Verfahren und Anordnung zur Abstands- und Druckmessung innerhalb einer Luftfeder
US20070015993A1 (en) * 2005-07-13 2007-01-18 Clemson University Microwave imaging assisted ultrasonically
WO2007008962A2 (en) * 2005-07-13 2007-01-18 Clemson University Microwave imaging assisted ultrasonically
WO2007008962A3 (en) * 2005-07-13 2009-04-16 Univ Clemson Microwave imaging assisted ultrasonically
US7725167B2 (en) * 2005-07-13 2010-05-25 Clemson University Microwave imaging assisted ultrasonically
JP2015090281A (ja) * 2013-11-05 2015-05-11 パナソニックＩｐマネジメント株式会社 超音波測定方法および装置

Also Published As

Publication number Publication date
DE3500640A1 (de) 1985-07-18
JPH0330105B2 (de) 1991-04-26
DE3500640C2 (de) 1986-07-03
GB2153997A (en) 1985-08-29
GB8500641D0 (en) 1985-02-13
JPS60146152A (ja) 1985-08-01
GB2153997B (en) 1987-06-10
CA1225733A (en) 1987-08-18

Similar Documents

Publication Publication Date Title
US5099693A (en) Apparatus for investigating a sample with ultrasound
US4597293A (en) Scanning acoustic microscope
WO1996022527A1 (en) Bore probe for tube inspection with guided waves and method therefor
KR920010328A (ko) 초음파 스펙트럼 현미경
US20020153805A1 (en) Optically controlled ultrasonic sensor and method of manufacture
US20170074831A1 (en) Focusing wedge for ultrasonic testing
US5381695A (en) Apparatus for investigating a sample with ultrasound
JPS5944582B2 (ja) 走査型音波顕微鏡
US4321696A (en) Ultrasonic transducer using ultra high frequency
US4208602A (en) Piezoelectric ultrasonic scanning head using a beryllium mirror
US4563898A (en) Acoustic microscope
US20020017141A1 (en) Ultrasonic detection method and apparatus and ultrasonic diagnostic apparatus
US5115414A (en) Conical ultrasonic wave deflection system
US4566333A (en) Focusing ultrasonic transducer element
US4700575A (en) Ultrasonic transducer with shaped beam intensity profile
US4909082A (en) Acoustic transducer for acoustic microscopy
EP0033751B1 (de) Ultra-Hochfrequenz verwendender Ultraschallwandler
JPS634142B2 (de)
EP0277785A2 (de) Akustischer Wandler
JP3404844B2 (ja) 超音波スペクトラム顕微鏡
JP2883051B2 (ja) 超音波臨界角探傷装置
JPH0611385A (ja) 横波音速測定装置及びこれを利用したヤング率及び／又はポアソン比測定装置
JPH0230769Y2 (de)
Ishikawa et al. Full-circular surface acoustic wave excitation for high resolution acoustic microscopy using spherical lens and time gate technology
JPS58147643A (ja) 超音波探触子

Legal Events

Date Code Title Description
AS Assignment

Owner name: HITACHI, LTD., 6, KANDA SURUGADAI 4-CHOME, CHIYODA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:KANDA, HIROSHI;ISHIKAWA, ISAO;KATAKURA, KAGEYOSHI;AND OTHERS;REEL/FRAME:004516/0790

Effective date: 19841220

FPAY Fee payment

Year of fee payment: 4

FEPP Fee payment procedure

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

FPAY Fee payment

Year of fee payment: 8

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
FP Lapsed due to failure to pay maintenance fee

Effective date: 19980701

STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362